Poly-1-butene resins

ABSTRACT

IMPROVED MOLDING RESINS COMPRISING A BLEND OF (A) ABOUT 70 TO 99.9% BY WEIGHT OF A SUBSTANTIALLY CRYSTALLIZABLE POLYMER OF 1-BUTENE SELECTED FROM HOMOPOLYMERS OF 1-BUTENE AND COPOLYMERS OF 1-BUTENE AND A DISSIMILAR A-OLEFIN OF 2 TO 12 CARBON ATOMS, SAID A-OLEFIN BEING PRESENT IN SAID COPOLYMER IN A CONCENTRATION OF UP TO ABOUT 20% BY WEIGHT AND (B) ABOUT 0.1 TO 30% BY WEIGHT OF A POLYMER OF ETHYLENE SELECTED FROM HOMOPOLYMER OF ETHYLENE AND COPOLYMER OF ETHYLENE AND A HIGHER A-OLEFIN.,, SAID HIGHER A-OLEFIN BEING PRESENT IN SAID COPOLYMER IN A CONCENTRATION OF UP TO ABOUT 10% BY WEIGHT, SAID POLYMER OF ETHYLENE HAVING A DENSITY OF AT LEAST 0.93.

United States Patent 3,733,373 POLY-l-BUTENE RESINS Richard L. McConnelland Doyle A. Weemes, Kingsport,

Tenn., assignors to Eastman Kodak Company, Rochester, N.Y. No Drawing.Filed Apr. 1, 1971, Ser. No. 130,518 Int. Cl. C08f 29/12 U.S. Cl. 260897A 12 Claims ABSTRACT OF THE DISCLOSURE Improved molding resinscomprising a blend of (A) about 70 to 99.9% by weight of a substantiallycrystallizable polymer of l-butene selected from homopolymers ofl-butene and copolymers of l-butene and a dissimilar a-olefin of 2 to 12carbon atoms, said u-olefin being present in said copolymer in aconcentration of up to about 20% by weight and (B) about 0.1 to 30% byweight of a polymer of ethylene selected from homopolymer of ethyleneand copolymer of ethylene and a higher a-olefin, said higherOL-Olfifil'l being present in said copolymer in a concentration of up toabout by weight, said polymer of ethylene having a density of at least0.93.

This invention relates to improved molding resins based on l-butenehomoand copolymers. More particularly, the invention is directed tol-butene homoor copolymers having improved moldability when blended withpolyethylene or copolymers of ethylene.

The usefulness of l-butene polymers as molding resins is seriouslylimited since they have a tendency to crystallize out of the melt as asoft, clear plastic commonly referred to as Form II and then graduallychange to a more thermodynamically stable form commonly referred to asForm I. During this transformation, the molded objects are tacky andwarp and become cloudy. Another problem associated with the molding ofpoly-l-butene is its low crystallization temperature. That is, the meltsuper-cools drastically prior to crystallization (melting point 130-135C.; crystallization point 76-77 C.). Thus, molded objects or parts ofl-butene polymers are very soft and the knockout pins puncture orpenetrate the part.

In attempts to alleviate these limitations of l-butene polymers,nucleating agents commonly employed with polypropylene such as acombination of aluminum isopropoxide and p-tert-butylbenzoic acid or thedibutylammonium salt of p-tert-butylbenzoic acid have been used.Unfortunately, these nucleating agents were found to have little effecton either the type of crystallinity formed initially in poly-l-butene orthe rate of change of Form II to Form I crystallinity.

One object of the invention, therefore, is to provide l-butene homoandcopolymer compositions having increased crystallization temperatures.

Another object of the invention is to provide an improved process forthe shaping into articles of l-butene homoand copolymers.

Thus, an additional object of the invention is to provide l-butenehomoand copolymers which may be molded and then removed from the moldwithout warpage or sticking to the mold or damage from knockout pins.

These and other objects of the invention are obtained by homogeneouslyblending about 0.1 to 30% by weight of an ethylene polymer having adensity of at least 0.93 with 70 to 99.9% by weight of a substantiallycrystallizable l-butene polymer. It has been found that the addition ofthese amounts of ethylene polymer will substantially increase thecrystallization point of polymers of 1- 3,733,373 Patented May 15,, 1973ice 20 C. That is to say, the compositions containing the ethylenepolymer crystallize at about 939-6 C. instead of about -76 C. Moreover,the compatibility of the blend of ethylene polymer and l-butene polymeris quite good so that the crystallinity-dependent properties of thel-butene polymer are not adversely affected.

In addition to the increased crystallization temperatures, it is foundthat the spherulite size of the l-butene polymer in the polyolefin blendof the invention is extremely small which indicates that the ethylenepolymer component of the invention is nucleating the l-butene polymerefiectively. Actual molding operations have demonstrated that thepolyolefin blends of the invention molded extremely well, released fromthe mold quite readily and the molded parts were not punctured or dentedby knockout pins.

The crystallizable l-butene polymer of the invention may be ahomopolymer of l-butene or a copolymer including random, block and graftcopolymers of l-butene and a polymerizable, dissimilar a-olefin of 2 to12 carbon atoms such as ethylene, propylene, l-pentene, l-hexene,l-heptene, 1-octene, l-dodecene, 4-methyl-l-pentene, 3- methyl-l-butene,vinylcyclohexane and the like. Crystallizable polymers are those whichhave a stereo-regular molecular arrangement that enables them tosolidify from a melt into a highly crystalline structure. The solidifiedcrystalline l-butene polymers have a high degree of crystallinity,usually at least 50%, often at least 70%, as determined by X-rayanalysis or other comparable means.

Poly-l-butene is conventionally made by the polymerization of l-buteneto stereoregular polymer in the presence of a conventional coordinationcatalyst. Such catalysts are, for example, combinations of violettitanium trichloride with organo-aluminum compounds such astrialkylaluminums or dialkylaluminum halides. Specific examples includeEt Al/TiCl (IsoBu) Al/TiCl -Et- AlCl/TiCl Et AlI/TiCl and the like. Hightemperature catalysts such as LiAlH TiCl may also be used. Thepolymerizate from the polymerizations may be solvent extracted, forexample, with methyl isobutyl ketone, diet'hyl ether and the like toremove any amorphous fraction and leave essentially crystallizablepolymer or, if desired, the total polymer formed, i.e., the unseparatedamorphous and crystallizable portions, may be used. The total polymerthus formed will be substantially crystallizable while containing somesmall amount of amorphous polymer.

Other operable catalysts include the three-component catalysts such asthose derived from violet titanium trichloride in combination withalkylaluminum dihalide or alkylaluminum sesquihalide and thirdcomponents such as hexamethylphosphoric triamide, dimethylformamide,tributylamine and the like. Specific examples include l/0.6/1 EtAlCl/(Me N) P(O)/TiCl 2/1/3 Et Al Cl (Me N) P(O)/TiCl and the like. Othertitanium trihalide compounds which may be used include violet titaniumtrichloride which contains aluminum chloride cocrystallized with theTiCl titanium tribromide, or titanium triiodide. Use of thesethree-component catalyst systems provides a highly crystallizablepolymer containing essentially no amorphous material.

Similarly, suitable copolymers of l-butene are made in the presence ofconventional coordination catalyst to form a substantiallycrystallizable product. The molecular weight of the l-butene polymer ofthe invention, as measured by its inherent viscosity in Tetralin at C.,will generally range from about 0.2 to about 5.0.

The ethylene polymer component of the blend of the invention has adensity of at least 0.93 and thus may be either medium or high densityethylene polymer prepared by any of the well-known polymerizationprocesses of the art. Medium density ethylene polymers generally have adensity of about 0.93 to 0.95 g./cc. and may be prepared, for example,by high pressure polymerizations involving free radical initiators. Thehigh density ethylene polymers are generally those having a density ofgreater than 0.95 g./cc. and may be prepared, for instance, by thepolymerization processes using supported chromium oxide catalysts or thecoordination catalyst described above. The inherent viscosity of theethylene polymers in Tetralin at 145 C. may vary from about 0.05 to 5,preferably about 0.1 to 2.0. The higher molecular weight ethylenepolymers usually have a melt index of about 0.1 to 20, most often about1.0 to 10 as measured by the standard ASTM D 1238 method. However,ethylene polymers of low molecular weight having melt viscosities of 50to 200,000 centipoises at 190 C. may be employed and are just asoperable. Although homopolymer of ethylene is the preferred ethylenepolymer component, the copolymers including random, graft and blockcopolymers of ethylene and up to 20% by weight of a higher l-olefin,usually of 3 to 8 carbon atoms such as propylene, l-butene, l-pentene,l-hexene, etc. may also be used, if desired.

The blending of the l-butene polymer component and ethylene polymercomponent may be accomplished in many ways known to those skilled in theart. Thus, a physical mixture of the polymer components in powder orpellet form can be blended together using conventional blendingequipment which includes Banbury mixers, Brabender Plastographs, hotrolls, extruders and the like. The blending or processing temperatureswill vary depending primarily on the molecular weight and melt index ofthe particular l-butene polymer. Normally the processing temperatureswill fall in the range of about 100 to 250 C.

As in other polyolefin compositions, other additives commonlyincorporated such as stabilizers, antioxidants, brightners,plasticizers, pigments fillers, and the like may be included in thecomposition of the invention.

The blends of the invention may be shaped into desired articles byshaping processes well known in the art as, for example, moldingtechniques including compression molding, injection molding, extrusionmolding and the like.

The following examples are included to further illustrate the presentinvention.

EXAMPLE 1 39.2 grams of crystallizable poly-l-butene (melt index 0.3) isblended with 0.8 gram of high density polyethylene (density 0.965g./cc.; melt index 0.6) on a Brabender Plastograph at 140 C. The mixingis continued for 6 minutes at this temperature under a nitrogenatmosphere. The melt index of this blend is 0.3. The followingDifferential Scanning Calorimeter (DSC) melting point andcrystallization point (C.P.) data are Obtained. The heating rate for theDSC thermogram is 20 C. per minute and the cooling rate is C. perminute.

4 The increased crystallization temperature of the blend demonstratesthat the polyethylene is nucleating the polyl-butene.

EXAMPLE 2 Additional blends of polyethylene with crystallizablepoly-l-butene are made in a manner similar to that described inExample 1. The following table indicates the amount of polyethylenepresent and the melting point and crystallization point data obtainedfrom DSC thermograms.

Melt

Polyethylene eoncn., index wt. percent blend M.P., C. C.P., C.

EXAMPLE 3 EXAMPLE 4 A blend of crystallizable poly-l-butene containing20% high density polyethylene is prepared in a manner similar to thatdescribed in Example 3. The blend has a melt index of 0.3. Thiscomposition molds well in the Reed Prentice molding machine and theobjects are removed from the mold without warpage or damage. The objectshave a good glossy appearance and good physical properties.

EXAMPLE 5 A crystallizable 10/90 propylene/l-butene copolymer having amelt index of 0.1 is blended with 2% polyethylene (density 0.965 g./cc.;melt index 5.3) in a manner similar to that described in Example 3. Thisblend molds well and the molded parts are readily removed from theinjection molding machine. The parts are extremely tough and have goodphysical properties.

EXAMPLE 6 Blends of polyethylene with crystallizable poly-l-butene orpropylene/l-butene copolymers are prepared according to the proceduredescribed in Example 1. The blends con- Material tain 2% polyethyleneand are identified in the table be- P01y 1 butene/polyethylene 35 9319W. The melt index of th components Of the blends lzoly-l l uicene 3gand DSC thermogram data on the blends are summarized 0 Y we 65 in thefollowing table.

. DSC data.

l-buteue polymer Melt index Polyethylene Melt index M.P., C. C.P., C (1)5/95 propylene/1.. 0.34 High density polyethylene 0.6 134 88 butenecopolymer. (density 0.965 g./ce.). (2) 15/85 propylene/l- 1.2. do 0.6-123 82, 59

butene copolymer. (3) Poly-l-bntene 200 do 2 130 94 (4) Poly-1-butene.0.1 L w viscosity polyethylene 2,000 cp at 132 92 (density 0.965g./cc.). (5) Poly-1-butene 6,000 ep. at :....de 4,000 cp at 127 89 1900. 190 (6) Poly-l-b 10 rln 130 92 EXAMPLE 7 Blends of crystallizablepoly-l-butene (melt index 0.3) with high density polyethylene having adensity of 0.965 g./cc. and a melt index of 0.6 are prepared in aBrabender Plastograph at 140 C. under a nitrogen atmosphere. Tensilespecimens are molded in a Watson-Stillman injection molding machine at350 F. and the samples are aged for 7 days prior to the determination ofphysical properties. The properties obtained are summarized in thefollowing table.

Polyethylene conc., wt. percent 20 30 Melt index 0. 3 0. 22 0. 24 0. 270. 29 Hardness, Rockwell R- 59 53 49 36 45 Hardness, Durometer D 66 6666 65 65 Tensile break strength,

1p.s.i 13, 700 10, 000 12, 000 11, 000 10, 600 E ongation, percenL. 2030 18 29 26 Stifiness, p.s.i.-..- 162,000 154, 000 131,000 137,000133,000 Impact strength, notched Izod at 23 C 5.56 1 1.6 1 3.02 1 3.021.76

1 Hinge break.

These data demonstrate that the blends of poly-l-butene containingpolyethylene have good moldability and the presence of the polyethylenedoes not adversely aifect the toughness or stiffness of thepoly-l-butene.

The following example is included to demonstrate the importance ofemploying an ethylene polymer component having a density of at leastabout 0.93 g./cc.

EXAMPLE 8 In a manner similar to that described in Example 1, 2% byweight of a low density (0.918 g./cc.) polyethylene having a melt indexof 0.3 is blended with poly-1- butene having a melt index of 0.3. Thefollowing melting point and crystallization point data are obtained onthe blend and poly-l-butene alone.

Material M.P., C. 0.1 C.

Poly-I-butenellow density P.E. blend 115 74 Poly-l-butene 134 75 Thesedata demonstrate that low density polyethylene does not increase thecrystallization point of poly-l-butene.

The blends of this invention provide a readily moldable plastic havingthe physical properties of poly-1- butiene. These blends can beextruded, compression molded, mechanically milled, cast or molded asdesired. These blends can be molded into a variety of shapes such asfilm, fibers, toys, glass bottles, pipe and the like.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:

1. A homogeneous blend comprising (A) about 70 to 99.9% by weight of asubstantially crystallizable polymer of l-butene selected fromhomopolymers of l-butene and copolymers of l-butene and a polymerizabledissimilar uolefin of 2 to 12 carbon atoms, said aolefin being presentin said copolymer in a concentration of up to about 20% by weight and(B) about 0.1 to 30% by weight of a polymer of ethylene selected from ahomopolymer of ethylene and copolymer of ethylene and a higher u-olefin,said higher u-olefin being present in said copolymer in a concentrationof up to about 10% by weight, said polymer of ethylene having a densityof at least 0.93.

2. The polyolefin blend of claim 1 wherein the l-butene polymer is ahomopolymer of l-butene.

3. The polyolefin blend of claim 1 wherein the polymer of ethylene is ahomopolymer of ethylene.

4. The polyolefin blend of claim 1 wherein the polymer of ethylene is acopolymer of ethylene and a higher aolefin.

5. The polyolefin blend of claim 1 wherein the l-butene polymer is ahomopolymer of l-butene and the polymer of ethylene is a homopolymer ofethylene.

6. The polyolefin blend of claim 1 wherein the polymer of l-butene is acopolymer of l-butene and propylene wherein the concentration ofpropylene in the copolymer is about 5 to 15% by weight.

7. A molded article of the polyolefin blend of claim 1.

8. A molded article of the polyolefin blend of claim 5.

9. A method of improving the molding of crystallizable polymers ofl-butene selected from homopolymers of 1- butene and copolymers ofl-butene and a polymerizable, dissimilar a-olefin of 2 to 12 carbonatoms, said m-olefin being present in said copolymer at a concentrationof up to about 20% by weight which comprises blending into saidcrystallizable polymer of l-butene prior to shaping about 0.1 to 30% byweight of a polymer of ethylene selected from homopolymers of ethyleneand copolymers of ethylene and a higher a-olefin, said higher a-olefinbeing present in said copolymer at a concentration of up to about 10% byweight, said polymer of ethylene having a density of at least 0.93 andsubjecting the resulting blend to shaping.

10. The method of claim 9 wherein the polymer of 1- butene is ahomopolymer of l-butene.

11. The method of claim 9 wherein the polymer of ethylene is ahomopolymer of ethylene.

12. The method of claim 9 wherein the polymer of l-butene is a copolymerof l-butene and propylene wherein the concentration of propylene in thecopolymer is about 5 to 15% by weight.

References Cited UNITED STATES PATENTS 3,634,551 1/ 1972 Stancell et a1260-897 A 3,050,497 8/1962 Young 260-455 3,250,825 5/ 1966 Martinovich260-897 FOREIGN PATENTS 677,933 1/21964 Canada 260-Dig. 35

MURRAY TILLMAN, Primary Examiner C. I. SECCURO, Assistant Examiner US.Cl. X.R.

